SOUTH LAKE TAHOE, Calif. (AP) — Divers searched a section of Lake Tahoe on Monday for one person still missing after seven others were killed when a boat capsized during a powerful weekend thunderstorm that whipped up high waves, authorities said.

Ten people were on board the 27-foot gold Chris-Craft vessel when it flipped Saturday afternoon near D.L. Bliss State Park on the lake’s southwest edge, U.S. Coast Guard officials said.

Two people were rescued immediately and taken to a hospital in unknown condition. Six bodies were recovered later Saturday and a seventh body was found Sunday evening, according to the El Dorado County Sheriff’s Office. Their names won’t be released until family members are notified, Sgt. Kyle Parker said.

The intensity of the thunderstorm surprised even forecasters, who had predicted some rain but nothing like the sudden squall that lashed the southern part of the lake around 3 p.m., said meteorologist Matthew Chyba with the National Weather Service office in Reno, Nevada. Winds topped 35 mph and waves swelled more than 8 feet .

“We weren’t expecting it to be so strong,” Chyba said Monday. He said temperatures in the area were 15 to 25 degrees below normal for this time of year, which could have contributed to the unstable air mass.

Eight-foot waves on Tahoe is “pretty significant,” Chyba said. “They were really rocking the lake.”

Lake Tahoe is a popular summer recreation destination for boaters, kayakers and paddleboarders. The pristine lake with very cold water straddles California and Nevada and is one of the deepest in the country, second only to Oregon’s Crater Lake.

Rescue crews and divers scoured the area Saturday evening for the remaining victims and resumed efforts Sunday morning before the Coast Guard eventually called off its search. El Dorado County sheriff’s deputies continued searching Monday with help from other agencies from California and neighboring Nevada, Parker said.

The storm Saturday cleared out within about two hours.

Chris Williams, a party boat operator with Tahoe Sports, was one of four company captains on the lake Saturday when the weather turned. He was stunned by the force of the storm and the size of the swells.

“We braved the weather and came back during some severe wave heights that have never been seen on Lake Tahoe,” Williams told the San Francisco Chronicle. “We were pushing the vessels to their maximum capabilities while making sure to keep all clients safely aboard.”

While all guests from Tahoe Sports charters returned safely, Williams said two boats from the company’s Tahoe Keys location broke from the pier and washed ashore.

Video obtained by KCRA-TV showed moored boats at a nearby marina crashing into one another amid strong gusts.